Hi
On 2017/8/9 7:48, Michał Mirosław wrote:
Fix lockdep splat introduced in v4.13-rc4.
[ 266.297226] ------------[ cut here ]------------
[ 266.300078] WARNING: CPU: 2 PID: 176 at /mnt/src/jaja/git/tf300t/include/linux/blkdev.h:657 mmc_blk_remove_req+0xd0/0xe8 [mmc_block]
[ 266.302937] Modules linked in: mmc_block(-) sdhci_tegra sdhci_pltfm sdhci pwrseq_simple pwrseq_emmc mmc_core
[ 266.305941] CPU: 2 PID: 176 Comm: rmmod Tainted: G W 4.13.0-rc4mq-00208-gb691e67724b8-dirty #694
[ 266.308852] Hardware name: NVIDIA Tegra SoC (Flattened Device Tree)
[ 266.311719] [<b011144c>] (unwind_backtrace) from [<b010ca54>] (show_stack+0x18/0x1c)
[ 266.314664] [<b010ca54>] (show_stack) from [<b062e3f4>] (dump_stack+0x84/0x98)
[ 266.317644] [<b062e3f4>] (dump_stack) from [<b01214f4>] (__warn+0xf4/0x10c)
[ 266.320542] [<b01214f4>] (__warn) from [<b01215d4>] (warn_slowpath_null+0x28/0x30)
[ 266.323534] [<b01215d4>] (warn_slowpath_null) from [<af067858>] (mmc_blk_remove_req+0xd0/0xe8 [mmc_block])
[ 266.326568] [<af067858>] (mmc_blk_remove_req [mmc_block]) from [<af068f40>] (mmc_blk_remove_parts.constprop.6+0x50/0x64 [mmc_block])
[ 266.329678] [<af068f40>] (mmc_blk_remove_parts.constprop.6 [mmc_block]) from [<af0693b8>] (mmc_blk_remove+0x24/0x140 [mmc_block])
[ 266.332894] [<af0693b8>] (mmc_blk_remove [mmc_block]) from [<af0052ec>] (mmc_bus_remove+0x20/0x28 [mmc_core])
[ 266.336198] [<af0052ec>] (mmc_bus_remove [mmc_core]) from [<b046aa64>] (device_release_driver_internal+0x164/0x200)
[ 266.339367] [<b046aa64>] (device_release_driver_internal) from [<b046ab54>] (driver_detach+0x40/0x74)
[ 266.342537] [<b046ab54>] (driver_detach) from [<b046982c>] (bus_remove_driver+0x68/0xdc)
[ 266.345660] [<b046982c>] (bus_remove_driver) from [<af06ad40>] (mmc_blk_exit+0xc/0x2cc [mmc_block])
[ 266.348875] [<af06ad40>] (mmc_blk_exit [mmc_block]) from [<b01aee30>] (SyS_delete_module+0x1c4/0x254)
[ 266.352068] [<b01aee30>] (SyS_delete_module) from [<b0108480>] (ret_fast_syscall+0x0/0x34)
[ 266.355308] ---[ end trace f68728a0d3053b72 ]---
Ouch... 7c84b8b43d3d *also* races the q->bypass_depth with blk layer, so
in principle, QUEUE_FLAG_BYPASS shouldn't be used outside the blk layer.
However we have to use it when we couldn't do these within
blk_cleanup_queue..
My current system couldn't boot with a modular mmc-blk, so i can't test
this case but obvious the race and lockdep case is here. Great to find
this fatal mistake, mea culpa.
Reviewed-by: Shawn Lin <shawn.lin@xxxxxxxxxxxxxx>
Fixes: 7c84b8b43d3d ("mmc: block: bypass the queue even if usage is present for hotplug")
Signed-off-by: Michał Mirosław <mirq-linux@xxxxxxxxxxxx>
---
drivers/mmc/core/block.c | 2 ++
1 file changed, 2 insertions(+)
diff --git a/drivers/mmc/core/block.c b/drivers/mmc/core/block.c
index e5938c791330..f1bbfd389367 100644
--- a/drivers/mmc/core/block.c
+++ b/drivers/mmc/core/block.c
@@ -2170,7 +2170,9 @@ static void mmc_blk_remove_req(struct mmc_blk_data *md)
* from being accepted.
*/
card = md->queue.card;
+ spin_lock_irq(md->queue.queue->queue_lock);
queue_flag_set(QUEUE_FLAG_BYPASS, md->queue.queue);
+ spin_unlock_irq(md->queue.queue->queue_lock);
blk_set_queue_dying(md->queue.queue);
mmc_cleanup_queue(&md->queue);
if (md->disk->flags & GENHD_FL_UP) {
--
To unsubscribe from this list: send the line "unsubscribe linux-mmc" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
